Field
The subject disclosure relates generally to re-saturation of unconventional core samples and analysis of such re-saturated unconventional core samples.
Description of Related Art
The petrophysical analysis of an unconventional core sample can be impeded because the majority of the producible hydrocarbons (and water) that are initially in such unconventional core sample escape from the unconventional core sample in the process of bringing the unconventional core sample from the downhole location where it was obtained to the surface. Routine analysis of conventional core samples includes core cleaning and re-saturation procedures, but for unconventional core samples, no methodology exists.
Economic production from a tight hydrocarbon reservoir is often accomplished by positioning horizontal wells in the reservoir that allows for effective stimulation by hydraulic fracturing. The position of such horizontal wells is often identified using logging and core data acquired from vertical wells that traverse the reservoir. Some of the notable factors that drive successful production from such tight hydrocarbon reservoirs include petrophysical properties, such as porosity, permeability, wettability, hydrocarbon saturation, and pore pressure. Other factors include geomechanical properties such as hydraulic fracture surface area and fracture conductivity. Therefore, accurate measurement of such petrophysical properties may improve performance from tight hydrocarbon reservoirs.
Nuclear magnetic resonance (NMR) core analysis applications have been shown to be useful for the characterization of fluids in shale formations. For example, an understanding of the NMR relaxation and diffusion properties of bound water and gas in gas shale samples has resulted in new methodologies for logging and interpretation in these reservoirs. Recently, interest has shifted to tight hydrocarbon reservoirs because of improvements in technology that make production from such tight hydrocarbon reservoirs economically viable. Laboratory NMR core analysis experiments have been attempted in combination with other methods, such as tight rock analysis (TRA) and mercury injection capillary pressure (MICP), to better characterize the rock from tight hydrocarbon reservoirs.